Drill bit



|. L. EARNHEART 2,179,689

DRILL BIT Filed 7 July 28, 1937 Zhwentor Patented Nov. 14, 19 39 IUNITED STATES PATENT OFFICE DRILL BIT Isaac Earnheart, Troy, Mont.Application July 28, 1937, Serial No. 156,160

a 1 Clam.

My present invention relates to improvements in drill bits foruswithpower machines or tools in earth boring. The bit of my inventionis especially designed forsinking holes in rocks etc., It as in miningoperations, and the bitis employed with an impact or endwise-concussiontype of drilling machine-tool having a rotary feed, and water passagesfor conveying water to the cutters or cutting edges, and forconveying-water and W debris from the cutting edges ofthe bit.

In carrying out my invention I provide a bit which is readily detachablefrom its shank, drill-bar, or drill-stem, in order that the bit may beremoved when necessary for sharpening; and w the cutting edges orcutters of the bit are fashioned witha bevel-face, and a longitudinallyextending front face forming part of a rearwardly extending notch, whichfacilitates sharpening and ire-sharpening of the cutters or cuttingedges. my These bevel-end-faces of the cutters may repeatedly be grounddown or sharpened, and in conjunction with the recess and the frontlongitudinal face of the cutter, each cutter may with facility be grounda number of times'for re- 25 sharpening, thereby increasing thedurability of a drill bit, and securing a maximum service for a bit.

The plural cutting edges of the bit arearranged tangentially of thecenter-hole andin 30 parallel pairs, perpendicular in their relation tothe axis of the bit, and these sharp cutting edges, under repeatedimpacts or end-concussions of the machine-tool, and the rotary feed ofthe bit, chipofi the rock, rather than'dig into the rock, 35 therebyreducing the strain onthe cutting edges or cutters, increasing thecutting speed of. the

bit, and-facilitating both the impact and the rotary-feed operations ofthe machine tool. The

rock thus chipped. ofl forms a debris that may readily be conveyed fromthe cutting edges, and

the flowing water clears away such debris from the cutters. I L Theinvention consists in certain novel combinations and arrangements ofparts involving the 51 parallel pairs of tangentially oifset cuttingedges,

the front longitudinally extending faces' and the bevel-end faces ofthe. cutters as will hereinafter be more fully set forth and claimed. Inaccompanying drawing I have illustrated one complete 50 embodimentof myinvention wherein the parts are combined and arranged according to modesI have thus far devised for the practical application of the principlesof my invention, and it will be understood that changes and alterationsW may be made in this exemplifying drawing, withoffset, parallel,cutting edges.

in the scope of my claim, without departing from I the principles of myinvention.

Figure 1 is a, plan view of the impact or concussion face of the bit,showing the arrangement of two pairs of bevel-edge, or chisel-putters ofthe bit.

Figure 2 is a side view of the bit showing it. threaded to the reducedthreaded end of a tool shank, stem, or drill bar. v

Figure 3 is a perspective View showing the four cutters, with theirbevel faces and frontlongitudinal faces.

' Figure 4 is a transverse sectional detail view of the bit at line tiof Figure 2. a

Figure 5 and Figure 6 are side views of a modified form of the bit withone pair of tangentially In the assembly view of Figure 2 a well knowntype of drill-rod, stem, or shank i, for a machine tool, is shown withits central water passage 2 ex- 20. --tendi ng longitudinallytherethrough, and this stem has a reduced, threaded head 3 upon whichthe bit t is detachably mounted. The bit, in the form of a cylinder,is'fashioned with a threaded socket ii to fit over the head 3, and it isalso fashionedwith a central water passage or duct 5 forming anextension of the passage 2 for supplying water to the cutters, and forconveying the water and debris to the rear as the cutting progresses. g1

The shank l forms part of an impactor concussion tool that is providedwith a rotary feed for the shank and bit, and thesemembers are slowlyrotated as the tool shank and bit are quickly agitated or reciprocated.

The impact end of the bit swells or ,flares out to form a diametricallyenlarged bit-head 8, and

the impact face of this head is fashioned with a plurality of cuttingedges in diametrically-offset pairs that radiate from the centralopening or $0 duct 6. In Figure l'it will be seen that the cutting edges9, II], II, and I2 are" arranged in tangentially-oifset parallel cuttersor cutting edges 9|I and 'I0l2, which are in advance of the rehiainderof the bit, and these sharp edges, by

faces l5 of the cutters. These notches also provide clearance for thesharpening operations of the cutters, and the bevel faces l5 are grounddownby a suitable machine tool, to form the sharp cutting edges. Thusthe length of the straight, flat front faces l3 of the bit-head, and thebevel-edge or face l5, permit of re-sharpening thecutters with facility,and the repeated sharpening operations prolong the life of the culty isusually met in sinking a perfect cylindrical hole.

When the bit, is penetrating a rock having a crevice at the side ofahole, and four cutting edges are employed as in Figure 1, it will beapparent thatthe work is uniformly distributed to three of the cutters,while the four cutter is passing through the crevice, thus equalizingthe impact by distributing the work of three of the cutters to stabilizethe performance of the bit.

In Figures 5 and 6 the bit is designed for use with a single pair oftangentially-ofiset cutting edges or cutters l0 and I2 instead of thetwo pairsused'in' Figure 1, and this type of cutter is adapted for avariety of uses where conditions are met dissimilar to those encounteredby the bit of Figure 1.

Having thus fully described my invention, what I-claim as new and desireto secure by Letters Patent is:

In a drill bithaving. an enlarged head and a centrallongitudinal waterpassage therein, said bit comprising four cruciform cutters havingrearwardly extending longitudinal notches between adjoining cutters,each cutter having a tangentially arranged cutting edge with its innerend terminating at the water passage, said cutting edges being arrangedin coplanar pairs at opposite sides of the'water passage, rearwardlybeveled end faces on the cutters, said notches each being formed byafiat front face on one cutter and a rearwardly curved face on anadjoining cutter, and said notches diminishing in area from the cuttingedges and each merging at a point in'the periphery of the head.

ISAAC L. EARNHEARTr

